Embodiments relate to a nonvolatile memory device and a cache read method thereof.
In recent years, there is an increasing demand for nonvolatile memory devices which can be electrically programmed and erased and which do not require the refresh function of rewriting data at specific intervals.
The nonvolatile memory device is configured to enable electrical program and erase operations and perform the program and erase operations by having threshold voltages to be varied when electrons are moved by a strong electric field applied to a thin oxide layer.
The nonvolatile memory device may include a memory cell array in which cells for storing data are arranged in a matrix form and a page buffer for writing data into specific cells of the memory cell array or reading data stored in specific cells thereof. The page buffer includes a bit line pair coupled to a specific memory cell, a register for temporarily storing data to be written into the memory cell array or reading data stored in a specific memory cell of the memory cell array and temporarily storing the read data, a sense node for sensing the voltage level of a specific bit line or a specific register, and a bit line selection unit for controlling whether or not to couple the specific bit line to the sensing node.
Of several read methods of the nonvolatile memory device, a cache read method for reducing the time that it takes to perform a read operation may be used. In the case where each page buffer includes two registers, one of the two registers performs a read operation, and the other of the registers performs an operation for outputting read data externally.
However, in the case where a read method using cache is repeatedly performed, parameters for the operations may also be changed. In particular, in the case where a read voltage (i.e., a reference of the read operation) is to be changed to accommodate the read method using cache, there is a need for a method of changing the read voltage while the cache read operation continues to be performed.